COLLISION WORK PERFORMED BY PATIENTS WITH PERIPHERAL ARTERY DISEASE

The goal of this study was to assess the differences in collision work performed by healthy, aged-matched controls compared to patients with peripheral artery disease (PAD) to provide foundations for an eventual exoskeleton design. Collision work is energy dissipated into the surrounding environment from impact, in this study’s case, upon heel strike. When designing an exoskeleton for patients with PAD, harvesting energy lost to collision work could be a valuable mechanism to improve walking performance. Devices designed to utilize the normally dissipated energy for assisting propulsion to improve walking performance are under-explored [1, 2]. The purpose of this study was to assess the validity of healthy, older individuals as a model for patients with PAD when investigating collision work as a primary exoskeleton design consideration. References [1] Kuo, A., et al. (2005). Exerc. Sport Sci. Rev.,33: 88-97 [2] Li, Q., et al. (2009). J. Neuroeng. Rehabil., 6: 22-22 [3] Donelan, J., et al.(2002). A. D. J. Biomech., 35: 117-12

Patients Walk Less Efficiently Following Revascularization

Peripheral artery disease (PAD) manifests from atherosclerotic blockages that greatly reduce lower-limb blood flow. Due to the reduced blood flow, patients with PAD have reduced ankle power during late stance. We hypothesized that revascularization to restore blood flow to the affected lower-limbs would lead to improved walking mechanics as demonstrated by increased walking efficiency. Walking efficiency will be defined as a percentage of positive work compared to absolute total work during the stance phase. Subjects completed over-ground walking trials at a self-selected speed before and 6-months following revascularization surgery. Three-dimensional kinematics were collected using 17 motion capture cameras (Cortex 5.1, Motion Analysis Corp, Santa Rosa, CA) with retro-reflective markers placed at anatomical locations according to a modified Helen Hayes marker set. Lower-limb joint powers were calculated using Visual3D (Visual3D, Germantown, MD, USA). Joint work was calculated as the integral of joint power in MATLAB 2018a. Ankle, knee, and hip work was normalized to percent of stance and divided into three phases: early, middle, and late. Work at all joints was summed for each phase. Paired t-tests were used to test for significance of revascularization on summed joint work at each phase with a Bonferroni corrected α-level of 0.05. Contrary to our hypothesis, patients with PAD produced more negative work during early stance and less positive work during late stance following surgery (